The invention relates to a fuel feed pump and a fuel feed system which is provided with a fuel feed pump for a motor vehicle, with a housing, in which a stator with a rotor of an electric drive motor is disposed, wherein between an inside wall of the stator and an outside wall of the rotor there is an internal space.
The German Patent Document DE 43 44 777 C2 already discloses a fuel supply system for a motor vehicle, where the fuel tank, the flow line system and the injection strip are insulated so as to be protected against loss of heat. However, what is not considered in this prior art fuel supply system is that the fuel feed pump also dissipates heat to the fuel, surrounding the fuel feed pump.
The object of the invention is to provide a fuel feed pump for a motor vehicle and a fuel feed system, provided with such a fuel feed pump, wherein the heating of a fuel, located in the fuel feed system, is reduced.
This problem, associated with the fuel feed pump of the invention, is solved by a fuel feed pump wherein the housing of the electric drive motor is surrounded by an external housing, forming an external space; wherein a total quantity of fuel, pumped by the fuel feed pump into the external housing, is divided in such a manner into two subquantities of fuel that the subquantity of fuel, required by a motor flows out of the fuel feed pump after flowing through the external space and the internal space; and wherein the other subquantity of fuel flows to a pressure regulator.
This problem, associated with the fuel feed system further includes a fuel tank from which the fuel feed pump pumps fuel to a motor and simultaneously to the pressure regulator, and that the subquantity of fuel, flowing through the fuel pressure regulator, flows back to the fuel tank.
The advantage of the fuel feed pump, according to the invention, is that the only amount of fuel that still flows completely through an interior of a housing of the fuel feed pump is that amount of fuel that is fed to an internal combustion engine. A subquantity of fuel is diverted from the housing of the fuel feed pump to a pressure regulator. In the fuel feed system, according to the invention, the diverted fuel flows from the pressure regulator back into a fuel tank of the fuel feed system.
The interior of the inventive housing of the fuel feed pump is constructed in such a manner that the fuel, fed to the motor, absorbs, first of all, the waste heat of the stator of the electric motor and then cools the outer surface of the rotor. By feeding the cold fuel to the surface of the electric drive motor it is guaranteed that even the outer surface of the housing of the inventive fuel feed pump will reach only a low temperature; and thus only very little heat can be dissipated by way of the surface of the housing of the fuel feed pump to the fuel, surrounding the fuel feed pump.
It is advantageous for the surface of the housing of the inventive fuel feed pump to be thermally insulated. Thus, the heating of the fuel of the inventive fuel feed system is reduced. By reducing the heat introduced into the inventive fuel feed system, the temperature of the fuel in the fuel tank remains lower. The result is simultaneously a lower rate of gas generation and thus reduced emission.